Burning CDs at different X's : 4X,12X,48X,52X

[ashubrads]

Can someone help me out here with details of burning a disc at different speeds 4X,12X,48X n all ??
Please tell me the significance behind different X's and what are their advantages and disadvantages.. ??

PS: Please let me know some technical reasons and implications behind it because Goggling (Search engines) gives only the qualitative view behind it with no technical aspects which I'm looking for.

Thanks in Advance.

- - - Updated - - -

Someone told me that it has something to do related with the "Multi Rate Digital Processors". But,that too doesn't help me much.

 

[betwixt]

I've never heard of "Multi Rate Digital Processors" so I doubt that's an explanation.

It is simply to do with the speed of the motor rotating the CD and the ability to pulse the writing laser fast enough to draw the pit pattern cleanly. Some very old CD's had quite a thick dye layer that diffused the pits badly so they had to be written at low laser power and fairly slowly. Modern discs have thin layers and improved chemicals in the dye layer which allow a 'cleaner' pit pattern to be drawn quickly. The 'X' is a reference to how fast the disc can be rotated, 1X is the lowest speed and also the speed of the original CDs, it's still the speed an audio CD rotates at when playing back. As they got better the disk and drive manufacturers pushed the speed higher and higher, hence 2x, 4x and so on up to 52x which I think is the fastest ever made. There is a real danger (it's happened to me) that old CDs read in high speed drives will shatter under centrifical forces. New discs are obviously designed to stay in one peice at top speeds!

There are no advantages in low speed, faster disks just save time when writing and reading them. You should note that the speed a CD rotates is not constant, they spin faster when the laser is nearer to the center of the disc in order to keep the bit rate high.

Brian.

 

[tpetar]

CDs still in usage ? 8-O

Problem exist when you try to write particular optical medium on higher speed. Bad optical medium material cannot support that speed of writing and quality of that recorded data is on question. Always is better to write data on some lower speed. The faster you burn a CD or DVD the higher chances you have for corruption due to imperfections on the disk.

The CD burner creates small bumps in the playing surface of the CD-R that the CD player can then detect. The spacing between each bump is critical to being able to detect and decode the data signal. But more importantly, the rising and falling edge (the beginning and end) of each bump is also critical, and this is the aspect that is most affected by different combinations of burn speed, disc media and the state of the laser.

If the bumps have shallow edges rather than nice sharp, crisp edges, the CD player extracts a very jittery signal with ambiguous timing references. Depending on how well designed the player is, a jittery output can often throw the rest of the data decoding system into a state of unreliability, leading to a higher error rate and thus a greater number of uncorrected errors.


Matching media and burning speed is critical. Don't underestimate the importance of the chemistry of the CD-R itself. Just like CD burners, not all CD-Rs are created equal and there is a significant difference in the quality of the media from different manufacturers, sometimes even from batch to batch from the same manufacturer.


http://www.osta.org/technology/cdqa5.htm
http://www.soundonsound.com/sos/nov04/articles/qa1104-3.htm


Image at ∼10,000x showing the data on a CD-R. A 700mb CD holds about 80 minutes worth of digital audio :

Data burned on a CD, magnified at 10,000x:

Best regards,
Peter

;-)

 

[pjmelect]

The faster you spin a CD/DVD at, the higher the jitter you get. So that to get a better burn you should burn at a slower speed. Saying that however some CD/DVD disks work better at certain speeds than others depending on the chemistry of the disk. I test my disks at different speeds and use Nero discspeed (a free program) to check on the quality of the burn by looking at the corrected error rate. Unfortunately manufacturers change the chemistry of their disks even for the same brand and type over time, so you need to check every time you buy a new batch. In general I burn at 4X speed as slower does not make any improvement, on some disks it is better to burn at a faster speed.

 

[ashubrads]

That means, burning a disc at low speeds has no advantages ??

 

[betwixt]

Well, you do get a little less jitter but whether that makes it more reliable or not depends upon the disc quality and drive quality. My personal preference is to burn one speed less than rated so I'm not pushing them to the limit. For example, if the disc says 52x I use 48x and if it says 48x I use 32x. I do this with CD, DVD and Blu-Ray discs and very rarely have a failure.

With RW discs (rewritable) I use the speed the manufacturer states, this kind of disk can become less reliable at lower speeds because the amount of laser exposure is more critical.

In case you didn't know, all discs have a section on them that describes the 'strategy'. This is the placed on the disc during manufacture and it describes the optimum laser power at different speeds. Unfortunately, it is often put on pirated discs with wrong information!

Brian.